Urinal Blockage Alarm

Urinal Blockage, Small Bore Pipe Blockage Alarm

Already in service with NHS Scotland, The Radio Data Networks Urinal Blockage Alarm is easy to retrofit to provide an early warning of blockages in small-bore, sewer stacks, pipes, ducts, gullies, and culverts.

Battery or 6V dc powered, the unit can be installed anywhere and can be used independently, connected to a local BMS system or alarm via an on-board isolation relay. The unit’s display is easy to read giving three levels of warning and a bleep whenever an issue is detected. 


Smale Bore Stack Monitoring System

Wireless Version of the Sewer Stack Alarm with Sentinel Receiver

The units may be also be supplied with a wireless interface permitting it to talk to a remote alarm panel via one of Radio Data Networks Sewer Sentinel Receivers or a Gateway Receiver.

The unit is also IoT+ compatible enabling remote monitoring of urinals, pipes and stacks via the intent. 


The sensing Catheter inserted into a 40mm pipe

Uniquely, the system is suitable for use in small bore pipes right down to 22mm. Operation is fully automatic and the unit checks for changes of levels in the stack once every 15-minutes using an air back-pressure monitor technique driven via a small compressor feeding a 6mm diameter catheter that is inserted into the pipe. The small diameter of the catheter makes the system perfect for use in urinals, showers and other small bore plumbed systems.

Where mains power is available, units can also be powered via a 6V dc mains adapter.

Wireless Version of the Sewer Stack Alarm with Gateway Receiver for Connection to a BMS system



  • Wall Mounted Polycarbonate Enclosure
  • Dimensions 12cm x 12cm x 5.5cm (ex-antenna)
  • Weight 500gm inc batteries
  • Sealing IP54

Detection / Trip Levels

  • Normal 0 < 30cm typical
  • Warning > 30cm Typical
  • High Alarm > 50cm Typical
  • High-High > 60cm Typical


  • Dual PCB construction
  • Microprocessor controlled
  • 4 x AA Battery Operation or external 6V adapter
  • Battery LED (Green)
  • Transmit Data LED (blue)
  • High -High Alarm – Red
  • High Alarm – Red
  • Warning (Amber) – Low Battery
  • Normal (Green)
  • Tactile Test/Reset Button
  • Relay – 2A 48V contacts with gold plating for BMS System

Wireless Option

  • Operating Frequency                                      869.85MHz
  • Compliance                                                        Radio Equipment Directive (CE) or UK Radio Regulations 2017 (UKCA)
  • License                                                                 Exempt
  • Transmit Power                                                10mW
  • Duty Cycle                                                           Less than 0.1%
  • Antenna                                                              ¼ wave fixed
  • Operating Distance                                          Free space 200m LOS